Individuals undergoing hematopoietic stem cell transplantation (HSCT) face severe cancer- and treatment-related stressors and experience heightened anxiety and depressed mood, which may influence the immune recovery process following transplant, impair quality of life, and ultimately increase risk of mortality. The proposed project will investigate whether psychological status pre- and post-transplant influences the reconstitution of innate and adaptive immunity and the occurrence of opportunistic infections during the 6 months following transplant. Participants will be 75 adults receiving autologous stem cell transplants at the University of Wisconsin Comprehensive Cancer Center. They will complete pre-transplant assessments of mood disturbance, perceived stress, and social support. Follow-up psychological, immune, and clinical assessments will occur at 1 and 3 months post- transplant. Granulocytes and natural killer cells will index recovery of innate immunity, and novel multicolor flow cytometry and immunophenotyping techniques will be employed to examine the reemergence and activation of monocyte and associated dendritic cell lineages during the first month, and subsequently the profile of B and T cell subsets at 3 months. Occurrence of viral, bacterial, and fungal infections will be determined from review of clinical history and medical records. Longitudinal mixed-effects and survival modeling strategies will be applied to discern the most salient predictors and magnitude of impact on post-transplant outcomes. The purpose of the study is to determine biobehavioral pathways by which psychological factors can hinder or facilitate the immune and clinical recovery following HSCT. This study would be the first prospective examination of the psychological influences on post-transplant immune reconstitution and is designed to set the stage for the development of an evidence-based psychosocial intervention to enhance quality of life and survival of HSCT patients. PUBLIC HEALTH RELEVANCE: The primary goal of this project is to examine the impact of psychological factors on the recovery of cancer patients after stem cell transplantation (HSCT). Both risk factors, such as mood disturbance, as well as potentially protective factors, including social support, will be evaluated prospectively in transplant patients with the aim of determining how those factors impair or facilitate the immune reconstitution that is associated with clinical complications and recovery. The project is a critical initial step for designing interventions and psychological services that will improve survival and enhance the quality of life of cancer survivors recovering from HSCT.